1. Field of the Invention
The present invention relates to a data recording device which is mounted in a disposable camera and which is used to record data, such as date and time of photographing, on a photographic film and, more specifically, to a data recording device for a disposable camera of the type which utilizes external light as the light source for recording data.
2. Description of the Related Art
A disposable camera consists of a photographic film housed in a case having a lens. A type of disposable camera is known which is equipped with a data recording device for recording data, such as date and time of photographing, in a predetermined area of the photographic film.
In a known disposable camera of this type, the data recording device does not use a dedicated light source for data recording but uses external light let in through an external light inlet, which is provided on the front side of the case, as the light source for the data recording, so that the disposable camera can be made smaller, more compact and less expensive. The light entering through the external light inlet is incident on a liquid crystal panel, in which a data pattern for data recording is formed as a light transmitting section. Due to the external light transmitted through the liquid crystal panel, the data pattern is transferred to and recorded in a predetermined area of the photographic film.
The above structure has a problem in that, when the external light is used, there is a possibility that a sufficient quantity of light will not be available for data recording. Due to the poor exposure for recording the data pattern, a clear data pattern may not be transferred to and recorded on the photographic film. This problem might be overcome by making the exposure time for data recording longer than the exposure time for photographing. However, this would require a shutter function for opening and closing the external light inlet for a duration different from that for the shutter for photographing. Such a shutter function is not suitable for a disposable camera, which should be made small, compact and inexpensive. To avoid this problem, it is desirable to mount a condensing lens on the external light inlet so as to condense the external light on the liquid crystal panel. A data recording device using a lens for condensing external light has been proposed by the present inventor in Japanese Patent Laid-Open No. 8-114841.
However, when a lens is used for condensing external light, the following problems must be overcome: first, with a condensing lens, it is impossible to efficiently condense the external light components other than the parallel incident light, such as scattered light. Further, when external light, i.e., sunlight, is used as the light source for data recording, the data pattern is recorded on the photographic film in a whitish color. When recorded in a whitish color on the photographic image, the data pattern is difficult to recognize and hard to read.